Was it okay to do this?

My (17m) parents gave me a $30 Starbucks card for Christmas. I get drinks often so I know they wanted me to treat myself. My little sisters best friend (14f) mentioned she was jealous because her mom just gave her clothes. I told her briefly well you could probably spend my card up and get away with it. I was half kidding but she jumped on the offer and said she would absolutely do it if I was sure. I said go for it and she added my gift card to her Starbucks app and promised she would not say anything. My parents have no idea the card went to her but they literally just gave it to me last night. Was it okay to let her use it up?